Olefin polymerization catalysts are of great use in industry. Hence, there is interest in finding new catalyst systems that increase the commercial usefulness of the catalyst and allow the production of polymers having improved properties.
Salen and or Salalen complexes have been used as transition metal components in the polymerization of alkenes, see, for example, U.S. Pat. Nos. 9,382,349; 9,464,148; 9,290,589; 9,193,813; 8,957,171; 8,957,172; 8,952,114; 9,045,568; 9,365,661; 8,937,137; 9,150,676; 9,200,099; and 9,200,100.
Inorganic Chemistry 2015, 54, 2204-2212 and Angewandte Chemie, International Edition 2014, 53, 9226-9230 describe the use of phosphasalen complexes as lactide polymerization catalysts.
Journal of Organometallic Chemistry 2006, 690, 3946-3950 describes the use of phenoxy-phosphinimine titanium and zirconium complexes as ethylene polymerization catalysts.
Other references of interest include: Organometallics (2013), 32(5), 1475-1483; Journal of the American Chemical Society 2012, 134, 20577-20580; Inorganic Chemistry 2012, 51, 2157-2169; Dalton Trans. 2011, 40, 10029-10037; Dalton Trans. 2009, 46, 10219-10222; Organometallics 2010, 29 (13), 2892-2900; Inorg. Chem. 2008, 47 (15), 6840-6849; Chem. Commun. 2009, 27, 4115-4117; Macromolecules 2008, 41 (22), 8603-8607; Organometallics 2007, 26 (20), 4955-4963; Polym. Sci., Part A: Polym. Chem. 2006, 44 (22), 6646-6651; Organometallics 2014, 33, 6193-6199.
There still is need for new catalyst compounds to widen the range of catalyst complexes available for superior performance in alkene polymerization. The performance may be varied with respect to the amount of polymer produced per amount of catalyst (generally referred to as the “activity”) under the prevailing polymerization conditions; the molecular weight and molecular weight distribution achieved at a given temperature; and/or the placement of higher alpha-olefins in terms of the degree of stereoregular placement.
Further, there is a need in the art for new catalysts with high activity that can produce ethylene and or propylene polymers.